Critical Security Vulnerability

SS7 Fraud Enablement Attacks

Attacks that facilitate financial fraud and identity theft through SIM cloning, authentication vector theft, and roaming fraud. These attacks enable complete subscriber impersonation and unauthorized service usage.

Educational Purpose Only

This information is provided for educational and security research purposes. Fraud enablement attacks can lead to significant financial losses and identity theft. Always obtain proper authorization before conducting security testing.

Fraud Enablement Attack Flow

Visual representation of SS7 fraud enablement attack sequence showing SendIMSI, SendAuthenticationInfo, and SIM cloning process

SendIMSI Attack

High

Obtains subscriber's permanent identifier for SIM cloning preparation

SendIMSI attacks obtain a subscriber's IMSI (International Mobile Subscriber Identity) from their temporary identifier (TMSI). The IMSI is a permanent identifier that can be used for SIM cloning and other fraud activities.

Fraud Applications:

• SIM cloning preparation
• Identity theft
• Subscriber profiling
• Targeted attack preparation
• Subscriber impersonation setup

Technical Details:

• Converts TMSI to permanent IMSI
• Requires SS7 network access
• First step in SIM cloning process
• Minimal detection footprint
• Can be performed remotely

SendAuthenticationInfo Attack

Critical

Most critical fraud-enabling attack enabling complete SIM cloning

SendAuthenticationInfo (SAI) is the most critical fraud-enabling attack. It requests authentication vectors (triplets or quintuplets) from the HLR, which can be used to clone SIM cards and impersonate subscribers on the network.

Obtained Information:

• Authentication vectors (RAND, SRES, Kc)
• Encryption keys
• Sufficient data for SIM cloning
• Network authentication credentials
• Ki derivation parameters (in some cases)

Attack Sequence:

Obtain target's IMSI via SendIMSI or location tracking
Send SendAuthenticationInfo request to HLR
HLR returns authentication vectors
Use vectors to program cloned SIM card
Register cloned SIM on network

Real-World Impact:

Enables complete SIM cloning, allowing attackers to make calls, send SMS, and use data services billed to the victim. Can result in massive financial losses and service abuse. Cloned SIMs can be used for identity theft, unauthorized access, and financial fraud.

Roaming Fraud via UpdateLocation

High

Enables fraudulent usage through impersonated roaming registration

Attackers impersonate roaming partners using UpdateLocation to enable fraudulent usage. Cloned SIM cards or stolen credentials are used to register on networks, generating charges that are billed through roaming agreements.

Fraud Mechanism:

• Impersonate legitimate roaming partner
• Register cloned SIMs on network
• Generate high-value traffic (premium SMS, international calls)
• Charges billed through roaming agreements
• Detection delayed due to settlement periods

Financial Impact:

Roaming fraud can result in millions of dollars in losses. The delayed settlement periods in roaming agreements allow fraud to continue for extended periods before detection. Attackers often generate high-value traffic such as premium SMS services and international calls.

Detection and Mitigation

SS7 Firewall Protection

Deploy SS7 firewalls to filter unauthorized authentication and subscriber information requests. Block SendIMSI and SendAuthenticationInfo from untrusted sources.

Firewall Rules:

• Block SendAuthenticationInfo from non-VLR sources
• Restrict SendIMSI operations
• Filter UpdateLocation from untrusted partners
• Implement source verification

Monitoring and Detection

Monitor SS7 traffic for suspicious authentication and subscriber information requests. Detect anomalies in authentication vector requests and roaming registrations.

Detection Indicators:

• Unusual SendAuthenticationInfo patterns
• Multiple authentication requests for same subscriber
• Unexpected roaming registrations
• High-value traffic from cloned SIMs

Related Security Resources